1. Technical Field of the Invention
The present invention relates to novel 4-heteroarylimidazole-2-thione compounds as industrial and useful products. It also relates to their process of preparation and to their formulation, as tyrosinase inhibitors, into pharmaceutical or cosmetic compositions useful for the treatment or prevention of pigmentary disorders.
2. Description of Background and/or Related and/or Prior Art
The pigmentation of the skin, in particular human skin, results from the synthesis of melanin by the dendritic cells, the melanocytes. The melanocytes comprise organelles, known as melanosomes, which transfer the melanin into the upper layers of keratinocytes, which are then transported to the surface of the skin via the differentiation of the epidermis.
Among the enzymes of melanogenesis, tyrosinase is a key enzyme which catalyzes the first two stages of the synthesis of melanin. Homozygous tyrosinase mutations result in oculocutaneous albinism type I characterized by a complete absence of the synthesis of melanin.
It is proving to be important to develop novel therapeutic approaches to treat disorders of pigmentation resulting from an increase in the production of melanin, for which there exists no treatment meeting all the expectations of patients and dermatologists.
The majority of skin-lightening compounds already known are phenols/catechols. These compounds inhibit tyrosinase but the majority of them are cytotoxic for the melanocytes as a result of oxidation phenomenon resulting in the formation of quinones responsible for this toxicity. This toxic effect risks bringing about permanent depigmentation of the skin.